Question

A 2µF capacitor is charged to 10 V, and then discharged through a 1.0 MΩ resistor.

a) What is the time constant of the discharge circuit? (Answer: 2 s)

b) What is the time taken for the potential difference across the capacitor to drop to 5 V? (Answer: 1.39

s)

Answer 1

$\tau=RC=1×10^6×2×10^{-6}$

$=2seconds$

$V=E(e^{\frac{-t}{RC}})$

$5=10(e^\frac{-t}{2})$

Solving for t,

t=1.3863 seconds